So-called selective herbicides having both safety for useful plants and herbicidal effects against undesired plants are actively used, but in actual use, even a highly selective herbicide has undesired effects against useful plants (simply referred to as phytotoxicity in many cases) depending upon various conditions such as weather conditions, soil conditions, varieties of the crop plants and the timing for the application of the herbicide in some cases. To cope with such an undissipated situation, use of various safeners has been studied, but the selection of the safener varies depending upon the type of the herbicide with which the safener is used in combination and depends on trial and error studies. For example, Patent Document 1 discloses herbicidal mixtures comprising cloquintocet as a safener.